Overview:
One CoBrowse Presentation is expired in CRM but still in Approved status on the Vault side after performing synchronization in CRM Online.
Root Cause:
One possibility is that the CRM Media Type of one slide of the presentation is set to the wrong type in the Vault side.
Example:
The slide below is an image but CRM Media Type is set to HTML.

Solution:
Be sure every slide of the presentation is set with the correct CRM Media Type on the Vault side.
Related Documentation:
Vault Documentation: Vault Help